But sasuke cannot learn it simply because he can't manipulate shape to perfection like Naruto. And Kakashi did not teach Sasuke the rasengan because at the time kakashi was still sasuke's teacher, he did not know it himself. Kakashi learned how to make the rasengan until shippuden.
You don't need wind nature to learn rasengan you need wind nature for rasenshuriken kakashi doesn't have wind nature, and plus it's because of plot no jutsu and i don't think just anyone can learn rasengan
wow some ppl here are stupid big time : RASENGAN DOES NOT NEED WIND NATURE WTF!!!
rasengan is simply chakra and shap manipulation and rasenshuriken is rasengan mixed with wind
ot: sasuke could def learn rasengan but he never would cuz that would be unentertaining if everyone uses rasengan but with proper training every ninja whith chakra could use rasengan
Why would he learn Rasengan? It's Naruto's signature move and Kakashi couldn't teach him anyway because at the time only Jiraya could make it (and Minato, but he was dead).